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dijous, 7 de març de 2013

The military’s next killer drone could be launched and landed aboard small surface warships, extending the reach of America’s robotic arsenal to more remote battlegrounds than ever before.
That is, if an ambitious new effort by Darpa, the Pentagon’s fringe-science wing, can overcome a technical challenge dating back to the 1980s. Namely: how to boost a drone to flight velocity without the benefit of a five-acre aircraft carrier deck, and without resorting to a speed- and range-limiting helicopter design.
The new Tactically Exploited Reconnaissance Node program
, or Tern, “envisions using smaller ships as mobile launch and recovery sites for medium-altitude long-endurance fixed-wing unmanned aircraft,” Darpa announced on Friday. That’s for unarmed spy drones as well as those armed for “strike” missions. The blue-sky researchers want to launch a prototype within 40 months.
Tern complements one of the Navy’s main robotic development efforts. The Navy wants a drone, equipped with missiles
and advanced spy gear, to take off and land from a full-sized aircraft carrier
, one of the hardest maneuvers in aviation. It’s currently experimenting with a 62.1-foot span, batwing-shaped prototype, called the X-47B
, which the Navy expects to launch the X-47B off a carrier deck at sea for the first time by May.
Except the jet-powered X-47B and the Unmanned Carrier Launched Airborne Surveillance and Strike System it will yield will be much farther out to sea than the Tern. “About 98 percent of the world’s land area lies within 900 nautical miles of ocean coastlines,” Darpa program manager Daniel Patt explained in the announcement. “Enabling small ships to launch and retrieve long-endurance UAVs on demand would greatly expand our situational awareness and our ability to quickly and flexibly engage in hotspots over land or water.”

Some of the specs Darpa wants: The as-yet-undesigned Tern drone must carry up to 600 pounds of sensors and weapons while flying out 600 to 900 miles from the launching ship. That places Tern in the same class as the Air Force’s iconic Predator and Reaper, both capable of flying 12 hours or longer while hauling cameras, missiles and satellite communications gear.
The launching ship could be as small as the USS Independence type of Littoral Combat Ship (LCS)
, which sports a 7,300-square-foot flight deck. The science agency’s concept art, shown above, depicts a somewhat Predator-esque drone flying over a Burke-class destroyer, the Navy’s workhorse warship, which is three times heavier than an LCS but has a slightly smaller flight deck.
Tern would fill a big gap in the Navy’s drone arsenal. The sailing branch currently flies the 10-foot-span ScanEagle drone
from destroyers and other vessels, and the Fire Scout robot helicopter
from LCS. In addition to developing the X-47B prototype and its descendants for aircraft carriers, it’s also got a land-based, unarmed patrol ‘bot
, the Broad Area Maritime Surveillance drone, based on the Air Force’s 737-size Global Hawk.
The latter have long range and high speed, but they’re tethered to the Navy’s 11 precious aircraft carriers and equally scarce land bases. The former can (in theory), take off from most of the Navy’s roughly 122 surface warships but lack range, speed and payload. What’s missing is a middleweight drone: a fast-flying, long-range, armed robot that takes up minimal deck space and is compatible with a wide range of surface ships.
One of Tern’s major technical obstacles is “devising a reliable launch and recovery technique,” according to Darpa. LCSs and destroyers don’t have the deck space for a long takeoff run — hence their reliance on the catapult-launched ScanEagle and vertical-liftoff robo-copters. In the 1980s and early ’90s, the Navy’s four World War II-vintage battleships carried the Pioneer drone, which was roughly twice the size of the ScanEagle and was boosted into the air with inelegant strap-on rockets.
The Pioneer landed aboard ship by awkwardly flying into a suspended net, whereas the ScanEagle catches a dangling wire
and the Fire Scout, of course, lands vertically
. A higher-performance, fixed-wing drone could require a smoother and more powerful takeoff boost than the older models anda less unwieldy means of returning to its launching vessel.
It’s worth noting that in the 1990s, U.S. helicopter-maker Bell designed a small tiltrotor drone call the Eagle Eye, which, like the company’s V-22 Osprey
, took off and landed like a helicopter but cruised like an airplane thanks to its rotating engine nacelles. Eagle Eye never found a buyer and went defunct. The Tern initiative could very well lead to a revival.
If Tern succeeds, Darpa is poised to significantly expand the Navy’s flying robotic arsenal, potentially transforming almost every warship into a mobile drone base. All the agency has to do is solve a decades-old launch and landing problem.